IBIC2012 - List of Authors (Sikora, J.P.)

Paper	Title	Page
MOPB55	Electron Cloud Measurements using Shielded Pickups at CesrTA	198
	J.P. Sikora, J.A. Crittenden, J.S. Ginsberg, D. L. Rubin CLASSE, Ithaca, New York, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. The Cornell storage ring was originally a positron/electron collider with beam energies ranging from 2 to 5 GeV. In 2008 it was reconfigured as the Cornell Electron Storage Ring Test Accelerator (CesrTA). An important part of the research at CesrTA is the study of the growth, decay and mitigation of electron clouds. Electron Cloud (EC) densities can be measured with a Shielded Pickup (SPU), where cloud electrons pass into the detector through an array of small holes in the wall of the beam-pipe. The signals produced by SPU have proved to be very useful in measuring the mitigating effect of different vacuum chamber surfaces - including differences in quantum efficiency as well as secondary and elastic yield. This has been accomplished through the careful comparison of observed signals with the output of the EC simulation code ECLOUD. We present example comparisons of data and simulation that show the effect of different surfaces as well as beam conditioning effects. In addition, some data has been acquired using a solenoid to produce a longitudinal magnetic field at the SPU. We will present our current understanding of the effect of a longitudinal magnetic field on SPU signals.

MOPB56	Electron Cloud Measurements using a Time Resolved Retarding Field Analyzer at CesrTA	201
	J.P. Sikora, M.G. Billing, J.V. Conway, J.A. Crittenden, Y. Li, X. Liu, D. L. Rubin, C.R. Strohman CLASSE, Ithaca, New York, USA K. Kanazawa KEK, Ibaraki, Japan M.A. Palmer Fermilab, Batavia, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, the US Department of Energy DE-FC02-08ER41538, DE-SC0006505 and US-Japan funding. The Cornell Electron Storage Ring has been reconfigured as a test accelerator (CesrTA) with positron or electron beam energies ranging from 2 GeV to 5 GeV. An area of research at CesrTA is the study of the growth, decay and mitigation of electron clouds in the storage ring. With a Retarding Field Analyzer (RFA), cloud electrons pass into the detector through an array of small holes in the wall of the beam-pipe. The electrons are captured by several collectors, so that the electron flux can be measured vs. horizontal position. Up to now, we have integrated the collector currents to provide DC measurements. We have recently constructed a new Time Resolved RFA, where the collector currents can be observed on the time scale of the bunch train in the storage ring. We present a summary of the design, construction and commissioning of this device, as well as initial beam measurements at CesrTA.

TUPB49	Electron Cloud Density Measurements using Resonant TE Waves at CesrTA	471
	J.P. Sikora, M.G. Billing, D.O. Duggins, Y. Li, D. L. Rubin, R.M. Schwartz, K.G. Sonnad CLASSE, Ithaca, New York, USA S. De Santis LBNL, Berkeley, California, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. The Cornell Electron Storage Ring has been reconfigured as a test accelerator (CesrTA) with beam energies ranging from 2 GeV to 5 GeV of either positrons or electrons. Research at CesrTA includes the study of the growth, decay and mitigation of electron clouds in the storage ring. Electron Cloud (EC) densities can be measured by resonantly exciting the beam-pipe with microwaves. The EC density will change beam-pipe's resonant frequency by an amount that is proportional to the local electric field squared of the standing waves. When the EC density is not uniform, it is especially important to know the standing wave pattern in order to obtain an absolute EC density measurement. We will present our current understanding of this technique in the context of new test sections of beam-pipe installed in August 2012. This will include bench measurements of standing waves in the beam-pipe, simulations of this geometry and recent EC density measurements with beam.

Paper

Title

Page

Electron Cloud Measurements using Shielded Pickups at CesrTA

198

J.P. Sikora, J.A. Crittenden, J.S. Ginsberg, D. L. Rubin
CLASSE, Ithaca, New York, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
The Cornell storage ring was originally a positron/electron collider with beam energies ranging from 2 to 5 GeV. In 2008 it was reconfigured as the Cornell Electron Storage Ring Test Accelerator (CesrTA). An important part of the research at CesrTA is the study of the growth, decay and mitigation of electron clouds. Electron Cloud (EC) densities can be measured with a Shielded Pickup (SPU), where cloud electrons pass into the detector through an array of small holes in the wall of the beam-pipe. The signals produced by SPU have proved to be very useful in measuring the mitigating effect of different vacuum chamber surfaces - including differences in quantum efficiency as well as secondary and elastic yield. This has been accomplished through the careful comparison of observed signals with the output of the EC simulation code ECLOUD. We present example comparisons of data and simulation that show the effect of different surfaces as well as beam conditioning effects. In addition, some data has been acquired using a solenoid to produce a longitudinal magnetic field at the SPU. We will present our current understanding of the effect of a longitudinal magnetic field on SPU signals.

MOPB56

Electron Cloud Measurements using a Time Resolved Retarding Field Analyzer at CesrTA

201

J.P. Sikora, M.G. Billing, J.V. Conway, J.A. Crittenden, Y. Li, X. Liu, D. L. Rubin, C.R. Strohman
CLASSE, Ithaca, New York, USA
K. Kanazawa
KEK, Ibaraki, Japan
M.A. Palmer
Fermilab, Batavia, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, the US Department of Energy DE-FC02-08ER41538, DE-SC0006505 and US-Japan funding.
The Cornell Electron Storage Ring has been reconfigured as a test accelerator (CesrTA) with positron or electron beam energies ranging from 2 GeV to 5 GeV. An area of research at CesrTA is the study of the growth, decay and mitigation of electron clouds in the storage ring. With a Retarding Field Analyzer (RFA), cloud electrons pass into the detector through an array of small holes in the wall of the beam-pipe. The electrons are captured by several collectors, so that the electron flux can be measured vs. horizontal position. Up to now, we have integrated the collector currents to provide DC measurements. We have recently constructed a new Time Resolved RFA, where the collector currents can be observed on the time scale of the bunch train in the storage ring. We present a summary of the design, construction and commissioning of this device, as well as initial beam measurements at CesrTA.

TUPB49

Electron Cloud Density Measurements using Resonant TE Waves at CesrTA

471

J.P. Sikora, M.G. Billing, D.O. Duggins, Y. Li, D. L. Rubin, R.M. Schwartz, K.G. Sonnad
CLASSE, Ithaca, New York, USA
S. De Santis
LBNL, Berkeley, California, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
The Cornell Electron Storage Ring has been reconfigured as a test accelerator (CesrTA) with beam energies ranging from 2 GeV to 5 GeV of either positrons or electrons. Research at CesrTA includes the study of the growth, decay and mitigation of electron clouds in the storage ring. Electron Cloud (EC) densities can be measured by resonantly exciting the beam-pipe with microwaves. The EC density will change beam-pipe's resonant frequency by an amount that is proportional to the local electric field squared of the standing waves. When the EC density is not uniform, it is especially important to know the standing wave pattern in order to obtain an absolute EC density measurement. We will present our current understanding of this technique in the context of new test sections of beam-pipe installed in August 2012. This will include bench measurements of standing waves in the beam-pipe, simulations of this geometry and recent EC density measurements with beam.